I think that Japanese dramas are better because after you're watched some Korean dramas it's getting little boring to start a new one because the plot is always so same... and that makes the drama very predictable...

But if you talk about acting, um, I think both Korean and Japanese can act... that's kinda hard question because it depense on a drama that what kinda acting there is. But if you see bad acting, it's probably from Japanese, but I think that's funny sometimes (like Ikuta Toma's acting in Hana Kimi, well I wouldn't say it was bad, but the character didn't feel humane, but he was hilarious =3).

there r pro n cons for both. if u wan romantic stories,then check korean dramas out.if u wan dramas about lessons of life and inspirational drama,the japanese produce good dramas for those example GTO,wonderful life,beautiful life,Good Luck.but most korean dramas have same story lines(guy meets girl,fall in love,a loves b,b loves a,c loves b,d loves a) and if u watch too much of those u will feel lame.

Korean dramas are good because they are longer and have more of a story, but sometimes they drag on too long.
Japanese dramas are good because they don't drag and are usually funnier, but then sometimes they are too short and you're left wanting to see more.
In the end I'm undecided because I like them both! ><